The implementation of a case by case review of at least 300,000 deportation proceedings, announced by the Department of Homeland Security last week, has left room for questions among immigrant advocate groups.

With this announcement, Homeland Security said it will implement prosecutorial discretion measures laid out in a June 2011 memo issued by John Morton, director of Immigration and Customs Enforcement (aka ICE).

Melissa Crowe, director of the Legal Action Center at the American Immigration Council, said on a conference call Monday, ”We are not sure how” Homeland Security’s commitment “will play out in practice” and what recourse individuals will have “if they believe their cases have been mischaracterized as high priority.”

Crowe added that in an ideal world, Homeland Security “officers throughout the country would stop issuing charging documents on low priority cases so they never enter the system to begin with.”

Mohammad Abdollahi of DREAM Activist writes in an email that “the decision from [Homeland Security] and Obama was nothing new, it pretty much just spelled out what they already had on the books.”

Last week’s announcement, based on the June 2011 memo issued by Morton, lays out a path to implement immigration law enforcement priorities put forward in a 2010 memo also issued by Morton that prioritized the detention and deportation of three groups: “aliens who pose a danger to national security or a risk to public safety,” “recent illegal entrants” and “aliens who are fugitives or otherwise obstruct immigration controls.”

That 2010 document adds, “Nothing in this memorandum should be construed to prohibit or discourage the apprehension, detention, or removal of other aliens unlawfully in the United States. ICE special agents, officers, and attorneys may pursue the removal of any alien unlawfully in the United States, although attention to these aliens should not displace or disrupt the resources needed to remove aliens who are a higher priority.”

Cecilia Muñoz, White House director of intergovernmental affairs, wrote last week that Homeland Security, “along with the Department of Justice, will be reviewing the current deportation caseload to clear out low-priority cases on a case-by-case basis and make more room to deport people who have been convicted of crimes or pose a security risk.”

“There is a lot of uncertainty about what could happen,” Jonathan Fried, executive director of We Count!, writes. He says that ICE “clearly did not implement” its June 2010 priorities.

Fried adds:

There is a lot of room for interpretation of who should or shouldn’t have their deportation proceedings dismissed. Just because someone is a low priority doesn’t mean that she or he won’t be deported. And finally, a lot may depend on who is making the decisions. If the same agents on the ground who have been resisting using their discretion and have falsely denounced previous statements from the administration as a “back-door amnesty” are going to be the ones making these decisions about whom to place in proceedings, the announced changes may amount to a lot less than we hoped.